The candidate is a third year Assistant Professor of pediatrics at the University of Pittsburgh School of Medicine and has a strong commitment to academic medicine as evidenced by his research endeavors and commitment to teaching. He has been interested in the role respiratory muscles play in the development of ventilatory failure in newborns. He is planning to expand the breadth of his research studies by acquiring new skills in muscle biochemistry and in vitro muscle contractile physiology during the training program proposed in the present application. These new skills are necessary to ensure successful future independent investigators of respiratory muscle development. The primary research goal of the proposed investigation is to determine the postnatal changes in the contractile, biochemical, and endurance properties of the external abdominal oblique muscle (an expiratory abdominal muscle of "mixed" fast and slow twitch fiber population when mature). Biochemical assessments to be performed include an analysis of this muscle's myosin contractile protein composition, its fiber succinate dehydrogenase (SDH) activity and its myofibrillar ATPase activity. We plan to correlate endurance properties with myofibrillar ATPase and SDH activities. Identical assessments will be performed on the costal diaphragm (an inspiratory muscle control of "mixed" fast and slow twitch muscle fiber population when mature), and the medial gastrocnemius (an appendicular muscle control of "mixed" fast and slow twitch fiber population when mature) in order to draw expiratory-inspiratory, ventilatory-appendicular, and rostral-caudal comparisons. By characterizing these developmental properties in expiratory and inspiratory muscle, we will deepen our understanding of the functional potential of the developing ventilatory pump.